1. Field of the Invention
The present invention relates to an apparatus for supporting and manipulating a testhead in an automatic test equipment system.
2. Description of the Related Art
Automatic test equipment (ATE) systems test semiconductor integrated circuits. FIG. 1 illustrates a conventional ATE system. A tester 1 generates test signals which are transmitted to a testhead 2 through cables 3. The testhead 2, as shown by the cut-away view, houses a plurality of printed circuit boards or pin cards 4. The test signals are transmitted from the pin cards 4 to contact pins or pogo pins 5. The contact pins 5 are represented schematically in FIG. 1 by arrows. It should be noted that the number of contact pins is much greater than what is illustrated in FIG. 1 and that the various elements of the ATE system in FIG. 1 are not drawn to scale.
The pogo pins 5 extend through the top surface 6 of the testhead 2. The pogo pins 5 are spring-loaded and press against the loadboard 7 to establish electrical contact for testing. The loadboard 7 is in turn a mount for socket 8. A device under test (DUT) 9 is inserted into socket 8 to establish electrical contact for testing. Thus, the test signals are transmitted from the tester 1 to the DUT 9 through the pin cards 4, contact pins 5, loadboard 7 and socket 8. The resulting signals from the DUT 9 are received by the tester 1 for evaluation through the same elements.
In various phases of testing such as debug, characterization and production testing, the testhead is connected to other equipment, such as automatic handlers and probers. Such connections require the tilting and rotating of the testhead as well as its mounting and dismounting. Because the testhead is large and heavy, specialized support structure is necessary to support and manipulate the testhead during testing.
FIG. 1 illustrates the testhead 2 supported by support structure 10. The support structure 10 is connected to a pneumatic or electrically controlled manipulator 11 for manipulating the testhead 2. The manipulator 11 is driven by internal electrical motor 12. However, such support structures with manipulators are very costly and bulky, require significant floor space, use power and energy and need extra manpower to operate. Furthermore, some operations such as dismounting are particularly complicated with the electrical or pneumatic connections.
It is an object of the present invention to provide an apparatus for supporting and manipulating a testhead that overcomes the above limitations of conventional support and manipulating mechanisms. The apparatus of the present invention provides an apparatus that supports the testhead through the use of a fixed axis about which the testhead can be rotated. The present invention can be employed utilizing simple mechanical means, thereby proving a cost-effective and space-efficient alternative to conventional mechanisms.
In one embodiment of the present invention, a testhead is supported and manipulated through manually-controllable shafts that connect a supporting frame to plates adapted to be mounted on opposite sides of the testhead.
The supporting frame has two members that extend from the base of the frame and along the side of the testhead. The end of each member has an opening for a shaft, and a shaft is disposed in each opening. The respective shafts are connected to hand levers that allow the shafts to be moved in a horizontal direction toward plates mounted on opposite sides of the testhead. Each plate has hole in which a flanged bearing is fitted. The testhead is mounted by moving the respective shafts through the flanged bearings inside the holes of plates. In this manner, the shafts support the testhead on two fixed pivots. The shafts also provide a fixed axis of rotation about which the testhead can be manipulated. For example, the testhead can be rotated relative to the shafts around the fixed rotation axis in a counter-clockwise direction.
Each plate can include a diagonal hole for controlling the speed of rotation. The diagonal hole begins at the surface of one side of the plate and continues through the plate to its opening. The flanged bearing has a cut through its length. A pressure screw is placed in the diagonal hole to abut the flanged bearing. When the pressure screw is tightened, the flanged bearing tightens on the shaft. Thus, a user can adjust the friction to control the speed of rotation of the testhead. It should be noted that other devices can be used to achieve damping of the rotation, such as tension straps and hydraulic vanes.
To lock the testhead in a particular position about the fixed rotation axis, each plate contains locking holes surrounding the plate opening and corresponding to a plurality of radial positions about the rotation axis. A locking pin is inserted into one of the locking holes to lock the testhead in a given position.
To change the radial position of the testhead, a lever arm is pulled out of a locking groove in a member of the frame. The lever arm rotates about a fixed vertical axis. Because the lever arm is connected to the locking pin, the pulling out of the lever arm pulls out or linearly displaces the locking pin from the locking hole of the plate (hereinafter referred to as the unlocked position). At this stage, the testhead can be rotated about the rotation axis. During rotation of the testhead, the lever arm is released. The lever arm is connected at the other end to a spring-loaded guide pin. The guide pin urges the lever arm to rotate back into locking groove. Because the lever arm is connected to the locking pin, the locking pin is pressed against plate between the previous locking hole and the next locking hole. When the locking pin encounters the next locking hole, it is forced into the hole and locks the testhead in the new radial position.
If a new radial position is not desired and the testhead needs to be dismounted, the testhead can easily be dismounted. With the locking pin withdrawn from the locking hole, the shafts are moved by their respective hand levers in a horizontal direction away from the plates mounted on opposite sides of the testhead. As the shafts leave the flanged bearings inside the holes of plates, the testhead is dismounted.
These and other features and advantages of embodiments of the present invention will be apparent to those skilled in the art from the following detailed description of the embodiments of the invention, when read with the drawings and the appended claims.